Drosera rotundifolia

Drosera rotundifolia (the common sundew or round-leaved sundew) is a species of sundew, a carnivorous plant often found in bogs, marshes and fens. One of the most widespread sundew species, it is generally circumboreal, being found in all of northern Europe, much of Siberia, large parts of northern North America, Korea, Japan and New Guinea.

The leaves of the common sundew are arranged in a basal rosette. The narrow, hairy, 1.3–5.0 cm long petioles support 4–10 mm long laminae. The upper surface of the lamina is densely covered with red glandular hairs that secrete a sticky mucilage.

A typical plant has a diameter of around 3-5 cm, with a 5–25 cm tall inflorescence. The flowers grow on one side of a single slender, hairless stalk that emanates from the centre of the leaf rosette. White or pink in colour, the five-petalled flowers produce 1.0–1.5 mm, light brown, slender, tapered seeds.[1]

In the winter, D. rotundifolia produces a hibernaculum to survive the cold conditions. This consists of a bud of tightly curled leaves at ground level.

The plant feeds on insects, which are attracted to its bright red colour and its glistening drops of mucilage, loaded with a sugary substance, covering its leaves. It has evolved this carnivorous behaviour in response to its habitat, which is usually poor in nutrients or is so acidic that nutrient availability is severely decreased. The plant uses enzymes to dissolve the insects – which become stuck to the glandular tentacles – and extracts ammonia (from proteins) and other nutrients from their bodies. The ammonia replaces the nitrogen that other plants absorb from the soil.

More info for the term: bog

Round-leaved sundew is distributed from Greenland and Newfoundland west
to Alaska. It occurs south along the Pacific coast to California and
inland as far as western Montana and western Colorado. In the East,
round-leaved sundew is found from Nova Scotia south to Georgia, Florida,
and Alabama and west to the Mississippi River, Iowa, and Minnesota
[14,19,21,44,45]. Round-leaved sundew is known from at least two
locations in west-central Montana [32]. In Colorado, it is known from
one bog in Gunnison County, a site that has been given special
protection [60]. There is also one record of round-leaved sundew from a
bog in Bottineau County, North Dakota [64]. Populations of round-leaved
sundew also occur in Europe and Asia [21,22,44].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
11 Southern Rocky Mountains

AL AK CA CO CT DE FL GA ID IL
IN IA KY ME MD MA MI MN MT NV
NH NJ NY NC OH OR PA RI SC TN
VT VA WA WV WI AB BC MB NB NF
NT NS ON PE PQ SK YT

Drosera rotundifolia fo. breviscapa Domin:
Canada (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Drosera rotundifolia L.:
China (Asia)
United States (North America)
Canada (North America)
Greenland (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Fujian, Guangdong, Heilongjiang, Hunan, Jiangxi, Jilin, Zhejiang [Asia, C and N Europe, North America].

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

More info for the term: adventitious

Round-leaved sundew is an insectivorous, short-lived perennial forb
arising from a basal rosette of leaves. The upper surface of the leaf
blades are covered with reddish, glandular hairs tipped with a sticky,
glutinous secretion that traps insects. The inflorescence is a
one-sided raceme with 2 to 15 flowers on a scape that is 2 to 10 inches
(5-25 cm) long. There may be one to seven inflorescences per rosette.
The fruits are capsules with numerous small seeds [8,20,21,41,44].

The root system of round-leaved sundew is usually shallow (less than 2.4
inches [6 cm]) [8]. It consists of a taproot - functional for less than
a year - which is replaced by mostly horizontal adventitious roots with
a few root hairs [8,37,50].

Round-leaved sundew compensates for the low available nutrients in its
habitat by catching and digesting insects [8,45,49,54]. Insects are
caught with the sticky glandular leaf hairs, and the leaf then folds
around the prey. The hairs secrete proteolytic enzymes which digest the
insect and enable the plant to absorb nutrients through its leaves
[37,45,52]. Insect capture is generally believed to enhance growth and
reproduction of round-leaved sundew [8,24,29,46,56]. It is
significantly correlated (p less than 0.01) with total leaf number, number of new
leaves formed, and total leaf area [46]. However, Stewart [50]
determined that round-leaved sundew did not benefit from insect capture
in field experiments in the Jefferson National Forest, Virginia. The
benefits of insectivory may be site-dependent; round-leaved sundew may
benefit most from insect capture on the most nutrient-poor sites.

Herbs perennial, with few fibrous roots. Stem unbranched, short, sometimes to 5 cm when growing in Sphagnum moss, forming a bulb at shoot tip during winter, not forming a tuber below ground. Leaves basal, dense, long petiolate; stipule 5-7-fid, 6-8 mm, scarious, closely adnate to petiole at base; petiole flat, 1-7 cm; leaf blades yellowish green or green to red, orbicular, suborbicular, or weakly reniform, 3-10 mm × 0.5-2 cm, with red, long capitate, sticky, glandular hairs. Inflorescences erect, scapiform, slender, 8.5-30 cm, glabrous; cincinni 1 or 2, 3-30-flowered; bracts subulate to linear, small; pedicels 1-3 mm. Sepals 5, united near base, green, ovate to oblong, ca. 4 × 1.5 mm, glandular, margin serrate. Petals white or tinged with pink, spatulate, 5-6 × ca. 3 mm. Stamens 5, 4-5 mm. Ovary ellipsoid-globose, ca. 3 mm; placentas 3; styles 3 or 4, deeply parted to base or entire, clavate; stigma simple. Capsule 3- or 4-valved. Seeds ellipsoid-globose; testa pouch-shaped, extended at each end. 2n = 20.

Drosera rotundifolia var. furcata Y. Z. Ruan.

More info for the terms: bryophyte, graminoid, peat, swamp

Round-leaved sundew is most often found in bogs, but also grows in
swamps, rotting logs, mossy crevices in rocks, or damp sand along
stream, lake, or pond margins [31,37,39,52,59]. It is generally
associated with sphagnum mosses and grows on floating sphagnum mats or
sphagnum hummocks [8,29,32,37,50]. It may also grow on peat soils of
other bryophyte or of graminoid origins [1]. In the northern part
of its range the sphagnum bogs in which round-leaved sundew grows are
generally found surrounding glacial lakes. In the Appalachians from
Pennsylvania to Alabama, the bogs are most often at confluences of
springheads, around seeps, or along streams rather than lake margins.
The same is true for sphagnum bogs of the southeastern coastal plain,
but there round-leaved sundew may also grow in grass-sedge bogs. In the
Pacific Northwest, sphagnum bogs are typically found along streams and
occasionally develop around high elevation seeps and shallow lake
margins in the northern Rocky Mountains [3,45].

Round-leaved sundew is usually confined to sites with a high water table
or high precipitation and humidity [8]. It requires continually moist
or wet situations [20]. Round-leaved sundew grows in organic acid soils
that are low in available nutrients (nitrogen and phosphorous, and
calcium [3,24,49,54]. According to Crowder [8], the normal range of the
water table on sites where round-leaved sundew grows is from 1 inch (2
cm) above to 16 inches (40 cm) below the soil surface. Flooding can be
tolerated for several weeks, but dry periods can only be tolerated for a
very short time. Lloyd [37] reported that it is not found on limestone
soils; high calcium concentrations may be toxic to the plant.

Round-leaved sundew grows in sedge meadow communities of the Huntingdon
Marsh in Quebec on peat underlain by clay at 24 inches (60 cm) or more.
The soil surface is slightly above or up to 10 inches (25 cm) below the
water table [2]. Round-leaved sundew has been reported as growing on
sites ranging from neutral pH (7.3) to very acidic (3.2) [18,38].
Acidic soils with low nutrient concentrations (nitrogen, phosphorous, or
calcium) seem to be the most common substrate [2,11,38,49,61].

In British Columbia, round-leaved sundew is an indicator of wet to very
wet, nitrogen-poor soils in boreal, cool temperate, and cool mesothermal
climates. It is associated with sphagnum moss in nonforested,
semiterrestrial communities [28].

An atypical site was found on Ile Perrot, Quebec, where round-leaved
sundew was growing on moderately dry, abandoned pastureland that
originally had been a swamp. The soil was well-drained loamy sand with
an average pH of 6.1. The site was "basically infertile" with extremely
low calcium and nitrogen concentrations [52].

More info for the term: bog

Round-leaved sundew is an indicator of bogs in the Northeast [24].

Tree species such as lodgepole pine (Pinus contorta), jack pine (P.
banksiana), Sitka spruce (Picea sitkensis), black spruce (P. mariana),
white spruce (P. glauca), western hemlock (Tsuga heterophylla), mountain
hemlock (T. mertensiana), eastern hemlock (T. canadensis), western
redcedar (Thuja plicata), northern white-cedar (T. occidentalis),
Alaska-cedar (Chamaecyparis nootkatensis), Atlantic white-cedar (C.
thyoides), tamarack (Larix laricina), balsam fir (Abies balsamea),
balsam poplar (Populus balsamifera), trembling aspen (P. tremuloides),
birch (Betula spp.), and red maple (Acer rubrum) occur as scattered
individuals or are present in forests surrounding the bogs or swamps
that round-leaved sundew inhabit [3,10,23,25,48].

Other species typically associated with round-leaved sundew include
leatherleaf (Chamaedaphne calyculata), bog Labrador tea (Ledum
groenlandicum), poison sumac (Rhus vernix), bog kalmia (Kalmia
polifolia), bog rosemary (Andromeda polifolia), bog cranberry (Vaccinium
oxycoccos), blueberries (Vaccinium spp.), willows (Salix spp.), common
buckbean (Menyanthes trifoliata), pitcher-plant (Sarracenia purpurea),
mountain bladderwort (Urticularia intermedia), slender bladderwort (U.
subulata), St. Johnswort (Hypericum spp.), sedges (Carex spp.), sheathed
cottonsedge (Eriophorum vaginatum), bluejoint reedgrass (Calamagrostis
canadensis), sphagnum mosses (Sphagnum spp.), Schreber's moss (Pleurozium
schreberi), and other mosses (Aulacomnium palustre and Polytrichum
juniperinum) [16,18,38,40,48,61].

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

K094 Conifer bog

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES10 White - red - jack pine
FRES11 Spruce - fir
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch
FRES19 Aspen - birch
FRES20 Douglas-fir
FRES22 Western white pine
FRES24 Hemlock - Sitka spruce
FRES27 Redwood
FRES28 Western hardwoods
FRES37 Mountain meadows

Forest understories, wet meadows, bogs, high moors, wet sunny open areas; sea level to 1500 m.

In Great Britain and/or Ireland:
Animal / predator
leaf of Drosera rotundifolia is predator of Diptera
Other: major host/prey

Animal / predator
leaf of Drosera rotundifolia is predator of Coenonympha pamphilus
Other: unusual host/prey

Animal / predator
bladder of Drosera rotundifolia is predator of Anisoptera
Other: unusual host/prey

More info for the terms: bog, marsh

Periodic autumn fires can prolong the life of some bogs by inhibiting
the invasion of woody plant species [45].

Round-leaved sundew, along with cattails (Typha spp.), horsetails
(Equisetum spp.), and common buckbean, are present in sedge meadow
communities that are maintained by fire in the Huntingdon Marsh, Quebec.
Fire is used to prevent the invasion of alders and willows [2].

In central Alberta, the burning of bog forests may revert the vegetation
to that of Labrador tea (Ledum spp.)-dominated moors, of which
round-leaved sundew is a component [36].

More info for the terms: bog, cover, frequency, peat, shrubs, swamp, wildfire

Round-leaved sundew colonizes recently burned peat surfaces [8,45]. At
the Acadian Forest Experimental Station in New Brunswick, round-leaved
sundew invaded a bog containing short, scattered tamarack after seasonal
burning. It was absent or measured at less than one stem per square
meter prior to burning, but seeds colonized the area in August and
germinated to produce small seedlings. However, the seedlings failed to
establish successfully and subsequently died [15]. Round-leaved sundew
frequency was relatively stable in the five summers following a late
March, 1974, wildfire in a Scotch pine (Pinus sylvestris) woodland in
Scotland; frequency ranged from 35 to 55 percent [53]. The plant may
have occurred in poorly-drained areas that were not completely burned.

Round-leaved sundew was present in a wetland community dominated by tall
shrubs in the Cicero Swamp Wildlife Management Area in New York that had
burned 94 years earlier. Up to 3.3 feet (1 m) of peat had been burned
on some sites, indicating a severe fire. Round-leaved sundew only had a
frequency of 1 percent and cover of 0.1 percent [33], possibly due to
the cover of tall shrubs.

Round-leaved sundew is most likely killed even by fast moving,
low-severity fires. However, fires in bogs are generally patchy and
round-leaved sundew probably survives in unburned microsites.

More info for the term: secondary colonizer

Initial-offsite colonizer (off-site, initial community)
Secondary colonizer - off-site seed

More info for the terms: bog, fire suppression, mesic, peat, shrubs

Frequent fire is necessary to maintain some of the bog habitats in which
round-leaved sundew grows. In these locations fire suppression has led
to the invasion of woody species from the surrounding forest. Frequent
surface fires remove the young woody plants advancing from bog edges.
Where woody vegetation is dense and has lowered the water table, fires
can be severe and may alter the subsequent composition of the vegetation
[45].

On moist savannahs of the southeastern coastal plain, fire suppression
has resulted in the exclusion of shade-intolerant species including
round-leaved sundew. Mesic savannahs succeed to flatwoods; wet
savannahs are quickly invaded by pocosin shrubs in the absence of fire.
When severe fires reduce peat depth or remove peat, grass-dominated
wetlands may replace the prefire vegetation [3].

Fire is important in lowland peat communities in Alaska. Sphagnum
development is slow after fire and burned peatlands are often invaded by
sheathed cottonsedge. This results in a shift from wet sphagnum bogs to
tussock communities. Round-leaved sundew, which inhabits the sphagnum
bogs, is able to survive on sphagnum hummocks between tussocks of
sheathed cottonsedge [5].

Many bogs may escape fire because of high water tables, or occur in
cold, wet climates with very long fire intervals.

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More info for the terms: bog, ferns, peat, shrubs, succession

Facultative Seral Species

Round-leaved sundew is very shade intolerant [28,50]. Since the plant
is so small, even graminoids and small shrubs may limit light
availability [50]. Shaded plants may not develop a rosette but instead
have a more spindly habit [8]. The encroachment of poison sumac,
speckled alder (Alder rugosa), and purple chokeberry (Pyrus floribunda)
into a kettle bog at Brown's Lake Bog Preserve in northeastern Ohio has
resulted in the "shading out" of characteristic bog species including
round-leaved sundew, pitcher-plant, and sphagnum mosses [12,63]. One
bog in Jefferson National Forest, Virginia, is kept in an early
secondary successional stage by periodic removal of ferns (Osmunda
spp.), alders, and other shade-producing plants. This treatment has
resulted in a proliferation of sundews (Drosera spp.) [50].

The adaptations of round-leaved sundew to nutrient-poor conditions
allows it to be very competitive and persistent in acid wetlands [45].
It has invaded disturbed sites in bogs after peat mining, ditching, and
burning [8,37,45,52]. In subarctic Manitoba, round-leaved sundew was
present in undisturbed bogs and in a bog that had been completely
cleared of vegetation 7 years earlier [48]. However, if succession
leads to the invasion of bogs by woody vegetation, round-leaved sundew
is easily shaded out as site conditions are altered [45]. In rich fens
round-leaved sundew is probably at a competitive disadvantage because of
higher species diversity [24,50].

Bog succession in general is not well understood [3,24]. Bogs can be
formed by the filling-in of lakes or ponds, or the paludification
process where forests are converted to wetlands [24]. Many bogs are
apparently stable and very long-lived, whereas others are ephemeral
unless frequently disturbed [3]. On Isle Royale in Lake Superior,
round-leaved sundew was present in mid-seral stages of succession from
rocky shore to forest and was also seral in bog succession, occurring
mostly between aquatic stages and bog forest [6,7]. The same general
pattern describes the role of round-leaved sundew throughout peat bogs
in eastern North America [9].

More info for the term: adventitious

Round-leaved sundew reproduces vegetatively or by seed [8,29,37,52].
Vegetative reproduction takes place when leaf buds form plantlets, or
when axillary buds below the rosette form a secondary rosette. As the
stem decays, the two separate [8,37]. Adventitious plants develop in
the autumn. They occur occasionally in the field but are often present
in greenhouse experiments, possible due to a high level of humidity
[52].

When flowers are open during the day, they are cross-pollinated by wind
or insects. Self-pollination may take place as flowers close in the
evening [45,50]. The fruits often persist unopened, and seeds are
released when the fruit rots [8]. The fusiform seeds are 0.06 to 0.07
inch (1.5-1.8 mm) long and 0.008 inch (0.2 mm) wide and have an inflated
testa. Air trapped in the testa makes the seed buoyant and capable of
floating for days on water surfaces. Seeds may be carried some distance
with snowmelt and flooding [52]. Plants flower in their first summer
and every year thereafter [8].

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More info for the term: hemicryptophyte

Hemicryptophyte

More info for the term: forb

Forb

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More info for the term: hibernaculum

Round-leaved sundew generally flowers from June to September throughout
its range [19,30,39,45]. Flowers open one per day, starting from the
bottom of the inflorescence [50]. Seed dispersal begins in July and
most seeds fall before winter. However, some may be found in dried
capsules in the spring [8]. Round-leaved sundew forms a hibernaculum
(tightly rolled leaf primordia) in the fall. The remaining leaves, and
frequently the roots, die back after the hibernaculum develops. The
hibernaculum opens in April or May of the following year [45,55,62].

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 7
Specimens with Barcodes: 18
Species With Barcodes: 1

Round-leaved sundew is protected in New York [31].

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

More info for the terms: bog, natural, peat

Clearing and drainage of peat bogs or swamps for peat mining, millpond
construction, access to timber, and agricultural purposes have resulted
in the decline of round-leaved sundew habitat by altering site
conditions in many areas [1,8,10,35,45]. Drainage also has an indirect
negative effect by diminishing the numbers of round-leaved sundew prey
that have aquatic larval stages [8].

Insectivorous plants, including round-leaved sundew, may add to the
nutrient pool on the nutrient-deficient sites where they most often grow
[40]. Round-leaved sundew itself apparently does not respond positively
to fertilization. The application of nitrogen, phosphorous, or a
combination of the two to nutrient-poor sites negatively affected the
growth of a natural round-leaved sundew population on the Jefferson
National Forest, Virginia. Plants were not as large, did not have as
many mature leaves, and did not produce as many flowers as plants on
sites without added nutrients. The negative effect may have been the
product of ion toxicity [50].

Microhabitat segregation among different sundews (Drosera spp.) at the
same site may influence the types of prey captured. Round-leaved sundew
and spatulate-leaved sundew (D. intermedia) in southern Germany occupied
different microhabitats and caught different kinds of insects, even
though they occurred together in the same bog [55]. Lists of insects
that have been captured as prey in the leaves of round-leaved sundew are
available [8,26,55].

Grazing apparently does not eradicate round-leaved sundew; it has been
found on wet grasslands of the British Isles that have been grazed by
both cattle and sheep [8].